Cat Creek Oil field.

Montacal oil well. Oil was discovered numerous times in Montana prior to 1919, but it wasn't until Frantz Oil Corp. struck "black gold" in December 1919 that the industry began to boom. The Denver-based company found the high-quality crude at extremely shallow depths in the Cat Creek field in Petroleum County east of Winnett. The easy access combined with the fact that the oil yielded about 50 percent gasoline made the venture remarkably profitable for Frantz Oil. Well production began in February of 1920, and its success drew oil companies from around the region to the Cat Creek field.